692 
Yendo.—The Development of 
Laminaria-Mke. frond increases in its length by intercalary growth, or, as 
Thuret calls it, by stipo-frondal growth, and adds to its thickness by the 
formation of cortex and medulla. 
The present writer has had opportunities for years of collecting and 
examining the early stages of development of various species of Lamina- 
riaceae on the coasts of Japan. In most cases the mode of development of 
these members coincided with what we had reason to expect. Among them 
Costaria Turneri has supplied especially favourable material for investiga¬ 
tion, and the results of the study proved interesting. The present paper is 
prepared to elucidate the development of this species in detail, as well as of 
Undaria pinnatifida and Laminaria sp., referring to some parallel accounts 
of other genera previously studied. 
I must not miss this opportunity of expressing my hearty thanks to 
Dr. D. H. Scott for so kindly taking the trouble of looking over the 
manuscript and proofs. It is due to this that the present writer has been 
able to publish his paper on the opposite side of the globe. 
I. Costaria Turneri. 
Costaria Turneri is an inhabitant of the North Pacific at low-water 
mark, descending to several fathoms of depth. It is found abundantly on 
the coasts of northern Japan, especially that of the Hokkaido Island (Yesso). 
In the vicinity of the Otaru Harbour, on the west side of the island, the 
plant begins to appear late in December. Numerous young fronds are found 
on rocks as well as on Sargassum Thunbergii , Rhodomela Larix , and some 
others which abound about there. These epiphytic specimens usually lose 
their anchorage as the fronds grow larger, and only those on rocks can 
survive to attain to their maturity. For the purpose of searching for the 
youngest individuals of the species, Rhodomela Larix serves as an especially 
suitable host. The latter is, at this season of the year, covered with 
Sphacelaria , Ulothrix , Bangia , &c.,and the spores of Costaria seem to seek 
their resting-places among the filamentous Algae. Several young shoots of 
Costaria are usually found growing together at a point. An examination 
of such points under a dissecting microscope generally reveals a number 
of minute fronds of much earlier stages. I shall first treat of the embryonal 
stages and then trace the more advanced forms. 
Embryonal Stages. 
It is a rather puzzling matter to give an exact definition of the 
embryonal stage in the life-history of Algae. The term can by no means 
be applied with clear limitations as in animal embryology. For Lamina- 
riaceous plants Setchell 1 includes in the embryonal stages the development 
1 Setchell : Post-embryonal Stages of the Laminariaceae. Univ. of Calif. Public., Botany, 
vol. ii, 1905, p. 1. 
